hi Sadd,
Thanks for your reply!
I have discussed with someone for the step4, he said that the individual tract paths have already thresholded, the group probabilistic map is not necessary to threshold again.
So I confuse about this step. what is the perfect way to do this step?
thanks again!
Yongxin Li
At 2012-12-12 22:20:38,"Saad Jbabdi" <[log in to unmask]> wrote:
>Sounds ok to me. You may also want to have some sort of a control tract.
>
>Saad
>
>On 12 Dec 2012, at 06:08, YX Li wrote:
>
>> hello all,
>> I was wondering what is the best way to analyse the fiber tracking results when running the probabilistic tractography. I have two group (trainings and conrols). Probabilistic tractography were performed. The seed region was defined from the FSLVBM analysis. I want to test if the training affect the FA values in the fiber tracts connecting the seed region. I can't sure if my statistic processing was right as following:
>>
>> 1. performed probabilistic tractography from seed mask to all other voxels in the brain
>>
>> 2. tractography in individual subjects was threshold (at least 50 streamlines had passed out of 5000)
>>
>> 3. individual tracts was then binarized, transformed to standand space, summed across subjects to produce group probability maps
>>
>> 4.these group probabilistic maps were threshold (present in a minimum of one-third of subjects) and then both group probabilistic maps were combined together as a mask
>>
>> 5. voxel-by-voxel-based comparison of FA values were performed between groups. The mask produce from step 4 was used as explicit mask.
>>
>> The validity of the step 4 is my major point want to verify .
>>
>> Thank you for your help!
>>
>> YX Li
>>
>
>--
>Saad Jbabdi
>University of Oxford, FMRIB Centre
>
>JR Hospital, Headington, OX3 9DU, UK
>(+44)1865-222466 (fax 717)
>www.fmrib.ox.ac.uk/~saad
